This invention relates to a method for determining the degradation that will occur in distillate fuel oils over a period of time.
During hydrocarbon processing, transportation and storage, the hydrocarbons deteriorate, particularly when subjected to elevated temperatures. The deterioration usually results in the formation of sediment, sludge, or gum, and can manifest itself physically by color deterioration. Sediment, sludge, or gum formation can cause clotting of the equipment or fouling of processing equipment, such as heat exchangers, compressors, furnaces, reactors and distillation systems, as examples. The fouling can be caused by the gradual accumulation of high molecular weight polymeric material on the inside surfaces of the equipment. As fouling continues, the efficiency of the operation associated with the hydrocarbon processing equipment, such as heat exchangers, compressors, furnaces, reactors and distillation systems decreases. The distillate streams, which can result in significant fouling, include the straight run distillates (kerosene, diesel, jet) naphthas, catalytic cracker feedstocks (gas oils), light and heavy cycle oils, coker napthas, resids and petrochemical plant feedstocks.
In the past, methods for determining the deterioration of fuel oil over a period of time, such as during storage, transportation or processing of the fuel oil, have relied on sampling the fuel after the period of time has past. Thus, they have been insufficient for predicting the deterioration of the fuel prior to such deterioration occurring. It is desirable to have a test method that is capable of determining not only the present state of a fuel oil but, also, is capable of predicting the state of a fuel oil after a period of time and predicting the rate of degradation of the fuel oil.